[claricecolin]

I agree with all of the above. They are calibrated for the individual user. If there is no choice but to purchase then ask Dr for a DME supplier that will rent. Most insurance companies that I am familiar with require at least 4 hours of use per day for 30 days to be in compliance so they will pay. I understand some have problems but I guess i was lucky and took to it immediately. Also you may have to try a few masks to get the one that works best for you.